Right, but I never said use a recording equalizer. I said develop whole new 500 series modules. As I
said, the EQ module could well be passive EQ, getting signal from the preamp module, then a gain
stage to bring everything up to the right line level.

Now that I read Paul's reply to Corey, I wonder if people misunderstood what I was proposing. Just
to be clear, I'm saying the 500 series format and frame because it's a pre-built and
pre-standardized form-factor and power source. But, the modules I described would have to be new
developments/builds. I don't know of any current 500 series modules that would work as disk
reproducers.

-- Tom Fine

----- Original Message -----
From: "Paul Stamler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, April 19, 2015 9:02 PM
Subject: Re: [ARSCLIST] "Best of both worlds" disk preamplifier


> On 4/19/2015 12:03 PM, Corey Bailey wrote:
>>
>> Let's start with the fact that active equalizers make better filters
>> than they do gain amplifiers. I proved this on the bench years ago. In
>> fact, it caused me to re-think the way I approached recording: listening
>> for what I wanted to remove instead of boosting what I thought was lacking.
>>
>> When boosting frequencies with an active equalizer (API, MCI, Neve,
>> Radial, etc.) you get unwanted phase distortion, not to mention running
>> out of headroom if you are talking about the amounts required for record
>> EQ. The reason is that, from a design standpoint, the vast majority of
>> equalizers used in pro audio equipment (at least, all of those you
>> mentioned) have the RC components in the feedback loop. Thus, the phase
>> distortion when boosting beyond 3dB or so.
>> In the case of record EQ, we are talking about only boosting the low
>> frequencies for playback but, that is the area where phase distortion
>> can be most difficult to hear. However, it is certainly measurable.
>>
>> My $0.02
>
> Corey's right; equalizers indended for recording use usually have bell-shaped curves, and are
> 2nd-order. De-emphasis curves for phono discs are 1st order, and trying to approximate them with
> recording-type equalizers is *very* approximate and will indeed lead to phase issues.
>
> Whereas record de-emphasis curves can be implemented accurately using simple RC filters. With
> appropriate buffering between them, they get the amplitude and phase right, to macvh the recorded
> curve.
>
> Peace,
> Paul
>
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